BUDAPEST (Reuters) - A Syrian migrant drowned in the Tisza river last week as he was trying to cross from Serbia to Hungary, police said on Monday, and the U.N. refugee agency blamed Hungary for adopting a policy that forced many migrants to take hazardous routes.

Police confirmed the death of the 22-year-old man in a reply to Reuters after the UN High Commissioner for Refugees issued a statement calling for an investigation into the accident.

The UNHCR said Hungary’s policy of admitting only 15-17 asylum-seekers daily at its two transit zones on the border with Serbia was forcing people into the hands of smugglers and towards alternative and often dangerous routes.

“The circumstances that led to this tragic death need to be swiftly and thoroughly investigated by the authorities on both sides of the border,” Montserrat Feixas Vihe, UNHCR’s Regional Representative for Central Europe said in a statement.

“Currently, there are several hundred asylum-seekers waiting to access asylum procedures in Hungary at the transit zones – the majority of them are women and children,” it added.

Police said a river patrol spotted two people swimming in the Tisza towards Hungary near the village of Roszke on June 1 shortly before 6 a.m.

After realising they had been spotted, they turned back towards Serbia but only one of them made it back. Police notified the Serbian authorities and, in a search, found the man’s body on June 3.

During the operation, police also rescued an Iraqi family of five from the river, Hungarian police said.

Prime Minister Viktor Orban has taken an increasingly anti-foreigner stance since migrants began pouring into Europe last year, building a heavily guarded border fence and rejecting an EU quota system to share out migrants among member states.

Hungary’s actions which include fast-track trials to punish those who breach its border fence, may conflict with international refugee and human rights conventions, the United Nations said last month.